1. Field of the Present Invention
The present invention relates to an ink set for ink-jet recording, an ink-jet recording method and an ink-jet recording apparatus.
2. Description of the Related Art
So-called ink-jet methods for ejecting a liquid or molten solid ink through an ink discharging port such as a nozzle, slit or porous film have been used for many printers since a printer using such a method is compact and inexpensive. A piezo ink-jet method for ejecting an ink by taking advantage of deformation of a piezoelectric element, a thermal ink-jet method for ejecting an ink by taking advantage of boiling of the ink by thermal energy, and the like are frequently used among the ink-jet methods since these methods enable high-resolution, high-speed printing. Ink-jet printers are used for printing on a paper sheet such as a regular paper sheet or an inkjet paper sheet as well as on a film such as an OHP sheet and on cloth.
One of the currently important objects of the ink-jet printer is high speed and high quality printing of images. For attaining compatibility between high speed printing and high quality printing of an image, Japanese Patent No. 2667401 discloses a method comprising the steps of allowing a liquid containing a cationic group-bearing compound to adhere on a recording medium, allowing the liquid to permeate into the recording medium, and forming an image by allowing an anion dye-containing ink to adhere on the surface of the recording medium immediately after the liquid has been absorbed into the recording medium and has disappeared from the surface thereof. However, image density may be insufficient in this method when the drying time of the ink is shortened, and long-term reliability may be insufficient when the images are printed using a small volume of drops.
Japanese Patent Application Laid-Open (JP-A) No. 2001-294788 discloses a color ink set for attaining high speed drying, high optical density and high image quality, wherein a black ink contains water and water-soluble solvents, the drying time of the black ink on a regular paper sheet is not longer than 5 seconds, color inks contain colorants, water, water-soluble solvents and a coagulant for coagulating the components in the black ink, and permeation time of the color inks into the regular paper sheet is not longer than 5 seconds. Although optical density, feathering and intercolor bleeding are excellent when pigments are used for colorants of the color inks in this method, long-term storability of images may not always be sufficient since the ink contains the coagulant.
JP-A No. 5-202328 discloses an ink composition containing synthetic dye materials having carboxylic groups, and an image forming method using a polyvalent metal solution in which the ink composition is applied after applying the polyvalent metal solution in order to provide a stable and water-resistant image without causing color bleeding. However, stable long-term storability of the ink may be deteriorated by adding a pigment in the polyvalent metal solution in this method.
As hitherto described, it has been impossible to simultaneously satisfy optical density, feathering, intercolor bleeding, drying time and long-term reliability by the conventional methods.